1) Field of the Invention
The present invention relates to a method of carbonization of organic waste such as sludge in rivers and seas, sludge of excrement, sludge of wastewater and residues of food, and an apparatus used therefor.
(2) Prior Art
Conventionally, organic waste such as sludge in rivers and seas, sludge of excrement, sludge of wastewater and residues of food generally has been incinerated in many cases. In these cases, such an environmental problem has occurred that dioxins have been generated in the process of incineration, and an environmental problem of energy consumption have occurred as the organic waste has contained much water wherefore much fuel has been required for incineration.
Therefore, with the enforcement of the recycling law, carbonization of the organic waste by using a carbonization furnace has been tried these years.
However, even in the carbonization of the organic waste by using the carbonization furnace, there has been a problem that the carbonization still has required much fuel, as the organic waste in a state of containing much water therein has been processed in the carbonization furnace.
Further, in the carbonization furnace, fuel has been burnt in order to raise temperature in the furnace, however, as the organic incinerator has contained much water therein, it has been necessary to burn much fuel. Accordingly, supply of much oxygen into the incinerator has required, wherefore there has been such problems that the organic waste has been incinerated to ashes but not carbonized, and dioxins have been generated.
The present invention presents a method of carbonization of organic waste and an apparatus therefor, in which gas being generated by carbonization of the organic waste in a carbonization furnace is burnt, and burning gas thereof is utilized to reduce water of the organic waste in a dryer, whereby the organic waste with less water therein can be surely carbonized with low energy.
The method of carbonization of organic waste of claim 1, comprises the steps of supplying organic waste to a dryer, reducing an amount of water in the organic waste by heating with high-temperature gas, supplying the organic waste to a carbonization furnace for carbonizing the organic waste in a high-temperature ambience, removing carbide from the carbonization furnace, incinerating gas, which is generated in the carbonization furnace, in a re-incinerating furnace, and supplying combustion gas of the re-incinerating furnace to the dryer as the high-temperature gas.
The apparatus for carbonization of organic waste of claim 2, comprises a dryer for receiving organic waste and reducing an amount of water contained in the organic waste by heating with high-temperature gas, a carbonization furnace for carbonizing the organic waste in a high-temperature ambience, the amount of water of the organic waste being reduced by means of the dryer, a re-incinerating furnace for incinerating gas which is generated in the carbonization furnace, a transmitting passage for transmitting combustion gas, which is generated in the re-incinerating furnace, to the dryer as the high-temperature gas, and a supply passage for supplying the organic waste to the carbonization furnace; the said organic waste being treated to reduce the amount of water by means of the dryer.
Further, in the apparatus for carbonization of organic waste of claim 3, as claimed in claim 2, it further comprises a flow passage provided with the dryer for the high-temperature gas generated in the re-incinerating furnace, wherein the dryer is heated with the high-temperature gas which flows in the flow passage of high-temperature gas and wherein the gas in the flow passage of high-temperature gas, which is used for heating, is exhausted.
Furthermore, in the apparatus for carbonization of organic waste of claim 4 and claim 5, as claimed in claim 2 or claim 3, a flow passage is provided with the dryer for the high-temperature gas generated in the dryer, wherein the dryer is heated with the high-temperature gas which flows in the flow passage of high-temperature gas and wherein the gas in the flow passage of high-temperature gas, which is used for heating, is exhausted.
In addition, in the apparatus for carbonization of organic waste of claim 6 and claim 7, as claimed in claim 4 or claim 5, the screw conveyer of the dryer and the re-incinerating furnace are connected to and communicated with each other by means of an air-supply passage to transmit evaporated gas, which is generated according to the reducing treatment of the amount of water in the organic waste.
Finally, in the apparatus for carbonization of organic waste of claim 8 and claim 9, as claimed in claim 6 or claim 7, a dust collector is interposed in the air-supply passage.
According to the method of carbonization of organic waste of the present invention, since water of the organic waste containing much water therein is reduced in a dryer in advance and then carbonization of the organic waste is carried out in a carbonization furnace, an amount of fuel to be burnt for raising a temperature in the incinerator can be cut down whereby lower energy consumption can be attained. In addition, an amount of oxygen supplied to the incinerator is held down to secure a state of oxygen deficiency, whereby carbonization of the organic waste surely can be attained.
Furthermore, the organic waste is dried in such a manner that gas generated by carbonization of the organic waste is burnt in a re-incinerating furnace and the combustion gas, being high-temperature gas, is supplied to the dryer, by which high-temperature gas the water in the organic waste is reduced. Therefore, it is not necessary to separately prepare fuel for the dryer, and energy saving can be achieved by recycling of energy.
In the method of carbonization of organic waste and the apparatus for carbonization of the organic waste used therefor according to the present invention, since the organic waste is supplied to the carbonization furnace after an amount of water contained therein is reduced in the dryer, an inside of the carbonization furnace can be heated to a high-temperature ambience with a small amount of fuel, wherefore energy saving can be attained. Further, since the amount of fuel for heating the inside of the carbonization furnace is reduced, an amount of the air supplied into the carbonization for burning the fuel can be lessened and the inside of the carbonization furnace can maintain a good state of oxygen deficiency, wherefore the organic waste can be surely carbonized without unexpectedly being incinerated to ashes.
In addition, the gas generated in the carbonization furnace is burnt in a re-incinerating furnace and the combustion gas is supplied to a dryer as high-temperature gas. The amount of water in the organic waste is reduced in the dryer by utilizing the high-temperature gas, wherefore it is not necessary to prepare fuel for heating the dryer separately, which means excellency in energy saving. Further, gas generated in a process of carbonization of the organic waste in the carbonization furnace is deodorized and made to be nonpoisonous by being burnt and decomposed, which also means excellency in terms of environment.
Moreover, in the apparatus for carbonization of the organic waste, the dryer provides a flow passage of high-temperature gas. The dryer is heated with the high-temperature gas flowing in the flow passage of high-temperature gas. In case it is so constructed that the gas in the high-temperature gas used for heating is exhausted, the dryer is heated by having the high-temperature gas generated in the re-incinerating furnace flowed in the flow passage of the high-temperature gas. By heating the dryer in the manners as mentioned above, the amount of the organic waste in the dryer is reduced, whereby energy saving can be attained, and the high-temperature gas is exhausted outside after the temperature of the high-temperature is lowered by giving the quantity of heat contained in the high-temperature gas to the organic waste in the dryer, which means excellency in terms of environment.
Further, in the apparatus for carbonization of the organic waste, the dryer comprises a screw conveyer 1a, which receives the organic waste, and a flow passage of high-temperature gas 1b, which encloses the screw conveyer 1a. In case a transmitting passage is connected to and communicated with a side of an inlet of the flow passage of high-temperature gas and an exhaust gas path is connected to and communicated with a side of an outlet of the flow passage of high-temperature gas, the flow passage of high-temperature gas is completely isolated from the inside of the screw conveyer, wherefore evaporated gas generated in a process of reducing treatment of water in the organic waste in the screw conveyer and the high-temperature gas flowing in the flow passage of high-temperature gas are not mixed with each other, whereby the high-temperature gas, after being used in the dryer, is exhausted outside while maintaining a clean state of being deodorized and becoming nonpoisonous in the re-incinerating furnace, which means excellency in terms of environment.
In addition, in the apparatus for carbonization of the organic waste, in case the screw conveyer of the dryer and the re-incinerating furnace are connected to and communicated with each other via an air-supply passage whereby the evaporated gas generated in a process of reducing treatment of water in the organic waste is transmitted to the re-incinerating furnace, the evaporated gas is burnt in the re-incinerating furnace and the combustion gas is recycled as high-temperature gas for heating the dryer, and energy saving can be attained.
Furthermore, as smelling gas and poisonous gas contained in the evaporated gas are burned and decomposed in the re-incinerating furnace, and are deodorized and made to be nonpoisonous, the gas exhausted outside is clean and is excellent in terms of environment.
Lastly, as the apparatus for carbonization of the organic waste comprises a dust collector interposed in the air-supply passage, the evaporated gas is supplied to the re-incinerating furnace after ultra-fine particles contained therein are removed, whereby the evaporated gas can be burnt well in the re-incinerating furnace and breakage of the re-incinerating furnace caused by burning of the ultra-fine particles can be prevented.